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Screw rod for extrusion foaming device and extrusion foaming device

A technology of extrusion foaming and screw, which is applied in the field of screw for extrusion foaming devices, which can solve the problem of inability to ensure effective and stable injection of foaming agent into polymer/uniform mixing of foaming agent, failure to ensure effective and stable injection of foaming agent, Problems such as uneven mixing of polymers and foaming agents can achieve the effect of increasing the pressure difference, improving the quality of finished products, and increasing the number of foaming nuclei

Active Publication Date: 2019-05-17
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the early stage, a single extruder was used to realize the functions of polymer plasticization, foaming agent injection, mixing, and cooling foaming, but there were problems such as difficult control of the processing process and uneven mixing of polymers and foaming agents. Through the extrusion and foaming technology of two extruders in series, the functions of polymer plasticization, foaming agent injection and polymer / foaming agent mixing, system cooling and other functions are separated, which can process microcellular polymer foam materials more stably
However, there are still some shortcomings in the stable injection of foaming agent, the uniform mixing of foaming agent and polymer, and the stability of polymer / foaming agent homogeneous system.
[0003] Chinese patent document CN 104325615 has designed a kind of supercritical CO 2 The twin-screw extrusion foaming device for preparing PET foam uses a combination of a single twin-screw and a static mixer. The disadvantage is that it cannot ensure effective and stable injection of foaming agent and uniform mixing of polymer / foaming agent
Chinese patent document CN 103273659 A has designed a kind of equipment for preparing carbon dioxide foamed extruded board through two serial extruders, each extruder is connected with a static mixer to realize the mixing of polymer and foaming agent, However, its disadvantage is that it cannot guarantee the effective and stable injection of blowing agent.
Chinese patent document CN103895146 A designed a continuous molding device for polymer microcellular foamed products. It is an improved injection molding device that connects an extruder and two sets of moldings. It cannot process continuous foam materials.

Method used

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  • Screw rod for extrusion foaming device and extrusion foaming device
  • Screw rod for extrusion foaming device and extrusion foaming device
  • Screw rod for extrusion foaming device and extrusion foaming device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0062] The raw material is polystyrene, the foaming agent is supercritical carbon dioxide, and the gas injection rate of carbon dioxide is 5ml / min; 180°C, on the second extruder 18: 180°C, 170°C, 160°C, 150°C, 140°C, the temperature of the foaming die 26 is 110-140°C; the screw speed of the first extruder 8 is 25 rpm Minutes, the screw speed of the second extruder 18 is 3 revs / min; Adopt capillary die, and the diameter of its discharge slit 28 is 2mm.

[0063] The performance indicators of the polystyrene foamed strips obtained in this example are as follows: the cell diameter is 5-40 μm, and the cell density is 5.0×10 8 ~1.2×10 9 cells / cm 3 , The expansion ratio is 10-25 times.

Embodiment 2

[0065] The raw material is polypropylene, the nucleating agent is nano silicon dioxide, the addition amount is 0.5% to 2.5% (mass ratio), the foaming agent is carbon dioxide, and the gas injection rate of carbon dioxide is 4ml / min; The heating temperature is set in sequence: first extruder 8: 190°C, 195°C, 195°C, second extruder 18: 195°C, 190°C, 180°C, 175°C, 170°C, foaming die 26 The temperature is 140-170°C; the screw speed of the first extruder 8 is 30 rpm, and the screw speed of the second extruder 18 is 2 rpm; a foaming flat slot die is adopted, and the discharge slot 28 The gap is 0.5-1.5mm.

[0066] The performance indicators of the polypropylene foam sheet obtained in this example are as follows: the cell diameter is 20-150 μm, and the cell density is 6.0×10 6 ~2.0×10 8 cells / cm 3 , The foaming ratio is 5 to 12 times.

Embodiment 3

[0068] The raw material is polyvinyl alcohol 1799; the plasticizer is water and glycerin, and the crosslinking agent is boric acid, wherein the plasticizer is added in an amount of 10% to 30% (mass ratio), and the crosslinker is added in an amount of 0.25 to 30%. 2% (mass ratio), the foaming agent is carbon dioxide, and the gas injection rate of carbon dioxide is 2.5ml / min; in the circulating cooling section 16 on the first extruder 8, a circulating cooling liquid with a temperature of about 50°C is added, and each The heating temperature of the heating section is set in turn: on the first extruder 8: 170°C, 180°C, 180°C, on the second extruder 18: 180°C, 175°C, 170°C, 160°C, 150°C, foaming The temperature of the die 26 is 105-140°C; the screw speed of the first extruder 8 is 15 rpm, and the screw speed of the second extruder 18 is 2 rpm; a foaming ring die is adopted, and the discharge seam 28 gap is 0.75 ~ 2mm.

[0069] The performance indicators of the polyvinyl alcohol fo...

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Abstract

The invention discloses a screw rod for an extrusion foaming device and an extrusion foaming device, and belongs to the field of extrusion foaming devices of microcellular polymer foam materials. Aimsat solving the problems existing in an existing microcellular polymer foam material extrusion foaming device, the device provides a screw rod capable of guaranteeing effective gas injection of extrusion equipment and an extrusion foaming device composed of the screw rod, the effective injection of the foaming agent and the uniform mixing of the foaming agent and the material can be ensured, and the quality of the forming material is ensured. According to the device, during the gas injection process of the foaming agent, the gas injection section arranged on the screw rod is matched with the gas injection port arranged on the gas injection device, regularly interval gas injection is realized in the screw rod rotating process, so that the gas injection pressure of the gas injection port canbe changed regularly, the pressure of the gas injection port at each time can be increased, the material melt can be prevented from being plugged into the gas injection port, the gas injection effectis ensured, and the material melt is prevented from overflowing reversely from the gas injection port.

Description

technical field [0001] The invention relates to the field of polymer material processing, in particular to the field of extrusion and foaming devices for microporous polymer foam materials, in particular to a screw for extrusion and foaming devices and an extrusion and foaming device composed of the screw. Background technique [0002] Since the concept of microporous polymer foam was proposed in the 1980s, it has received more and more attention due to its special structure and properties. The preparation methods of microcellular polymer foam mainly include batch foaming method, injection foaming method and extrusion foaming method. The blowing agent used is mainly supercritical carbon dioxide and nitrogen. The batch foaming method is a discontinuous processing method suitable for small-sized samples, which is not suitable for industrial production. Injection foaming technology, represented by Mucell technology developed by MIT, has been widely used commercially, but beca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B29C69/02B29C44/20B29C44/34
Inventor 白时兵贾迎宾王琪刘鹏举李正坤王刚
Owner SICHUAN UNIV
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